Sensor abnormality detection device

Abstract

To provide an abnormality detection device capable of enhancing frequency of detection of an abnormality of a fuel residual amount sensor.SOLUTION: An abnormality detection device is for a sensor that detects residual amount of fuel on the basis of a position of a float floating on a liquid surface of the fuel in a fuel tank of a vehicle. The abnormality detection device for the sensor includes: a calculation section that calculates an integrated value of injection amount of the fuel; an acquisition section that acquires acceleration of the vehicle; a detection section that detects an abnormality of the sensor on the basis of change of an output value of the sensor when the integrated value reaches a threshold value; and a setting section that sets the threshold value lower as an absolute value of the acceleration becomes larger.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an abnormality detection device for a sensor. [Background technology]

[0002] The fuel level sensor detects the remaining amount of fuel based on the position of a float that floats on the fuel surface in the fuel tank of a vehicle. If the float is stuck, the position of the float does not change sufficiently even if the fuel level fluctuates, and the fuel level sensor cannot correctly detect the remaining amount of fuel.

[0003] Patent Document 1 describes that when the amount of change in vehicle speed is greater than a judgment value and the amount of change in the output value of the fuel level sensor is smaller than a predetermined sticking judgment threshold value, it is judged that the fuel level sensor is abnormal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-220109 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the technology described in Patent Document 1, for example, when the vehicle is stopped or traveling at a constant speed, the change in vehicle speed does not exceed the judgment value, and abnormality detection of the fuel level sensor is not performed, so a sufficient detection frequency cannot be ensured.

[0006] SUMMARY OF THE PRESENT DISCLOSURE The present invention has been made in consideration of the above-mentioned problems, and has an object to provide an abnormality detection device that can increase the frequency with which an abnormality in a remaining fuel amount sensor is detected. [Means for solving the problem]

[0007] The sensor abnormality detection device of the present invention detects the remaining amount of fuel based on the position of a float floating on the surface of fuel in a fuel tank of a vehicle, and has the following features: a calculation unit that calculates an integrated value of the fuel injection amount, an acquisition unit that acquires the acceleration of the vehicle, a detection unit that detects an abnormality in the sensor based on a change in the output value of the sensor when the integrated value reaches a threshold value, and a setting unit that sets the threshold value lower as the absolute value of the acceleration becomes larger. Effect of the Invention

[0008] According to the present invention, it is possible to increase the frequency with which an abnormality in the remaining fuel amount sensor is detected. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram showing an example of a vehicle. [Diagram 2] FIG. 4 is a diagram illustrating an example of map data. [Diagram 3] 5 is a time chart showing an example of abnormality detection of a fuel level sensor. [Figure 4] 4 is a flowchart showing an example of an abnormality detection process for a fuel level sensor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Vehicle configuration) 1 is a configuration diagram showing an example of a vehicle 9. The vehicle 9 is, for example, a gasoline vehicle or a hybrid vehicle. The vehicle 9 has an ECU (Electronic Control Unit) 1, a fuel tank 2, an engine 3, an accelerator sensor 40, a vehicle speed sensor 41, and a multi-information display (display) 42.

[0011] The accelerator sensor 40 detects the opening degree of an accelerator pedal (not shown). The vehicle speed sensor 41 detects the vehicle speed of the vehicle 9. The accelerator sensor 40 and the vehicle speed sensor 41 output their respective detection values ​​to the ECU 1. The display 42 displays various information input from the ECU 1.

[0012] The engine 3 is an example of an internal combustion engine. The engine 3 is a drive source for the vehicle 9. If the vehicle 9 is a hybrid vehicle, a motor is further provided as another drive source.

[0013] The engine 3 is provided with an intake pipe 30 that takes in outside air. The intake pipe 30 is provided with a fuel injection valve 31. The fuel injection valve 31 receives fuel from the fuel tank 2 via a supply pipe 32 and injects the fuel into the intake pipe 30. At this time, the ECU 1 controls the amount of fuel injected by the fuel injection valve 31. The fuel and intake air are mixed in the engine 3 to become an air-fuel mixture, which is ignited and combusted to drive a crankshaft (not shown) of the engine 3.

[0014] The fuel tank 2 stores the fuel F. A supply pipe 24 for supplying the fuel F is connected to the fuel tank 2. A fuel pump 23 is provided at an upper portion inside the fuel tank 2. The fuel pump 23 supplies the fuel F to a fuel injection valve 31 via a supply pipe 32.

[0015] In addition, a fuel level sensor 20 and a float 21 are provided in the fuel tank 2. The fuel level sensor 20 is an example of a sensor, and detects the remaining amount of fuel F based on the height position of a float 21 floating on the liquid level S of the fuel F in the fuel tank 2 of the vehicle 9.

[0016] The height position of the float 21 changes as the fuel F decreases and the liquid level S changes. Fig. 1 shows an example of the height position of the float 21 changing from Ha to Hb. The float 21 is connected to a rotor 200 provided in the fuel level sensor 20 via an arm 22. The rotor 200 rotates in accordance with the movement of the arm 22 in response to the change in the height position of the float 21. The fuel level sensor 20 outputs the height position of the float 21 to the ECU 1 as the remaining level of fuel F based on the rotation angle of the rotor 200.

[0017] The ECU 1 is an example of an abnormality detection device for a fuel level sensor 20. The ECU 1 includes an arithmetic circuit such as a microprocessor and a storage circuit such as a memory. The ECU 1 includes a level detection unit 10, an abnormality detection unit 11, an injection amount calculation unit 12, an acceleration calculation unit 13, a threshold setting unit 14, and a memory 15. The level detection unit 10, the abnormality detection unit 11, the injection amount calculation unit 12, the acceleration calculation unit 13, and the threshold setting unit 14 are realized by at least one of software and hardware, for example.

[0018] The level detection unit 10 receives an output value of the remaining amount level of fuel F from the fuel level sensor 20. The level detection unit 10 outputs remaining amount information to the display 42 based on the output value. The display 42 displays the remaining amount information. The level detection unit 10 also outputs the output value of the remaining amount level to the abnormality detection unit 11, for example, periodically.

[0019] The injection amount calculation unit 12 is an example of a calculation unit. The injection amount calculation unit 12 calculates the injection amount per unit time of the fuel injection valve 31. The injection amount calculation unit 12 calculates a torque command value from, for example, the detection values ​​of the vehicle speed sensor 41 and the accelerator sensor 40, and controls the opening and closing of the fuel injection valve 31 so that an injection amount according to the torque command value is injected.

[0020] The injection amount calculation unit 12 calculates an integrated value of the injection amount. Here, the integrated value of the injection amount is substantially the amount of decrease in the fuel F in the fuel tank 2. The injection amount calculation unit 12 calculates the integrated value of the injection amount, for example, by integrating the injection amount. The injection amount calculation unit 12 outputs the integrated value to the abnormality detection unit 11, for example, periodically.

[0021] The abnormality detection unit 11 is an example of a detection unit. When the integrated value reaches a threshold value, the abnormality detection unit 11 detects an abnormality in the fuel level sensor 20 based on a change in the output value of the fuel level sensor 20. Therefore, the abnormality detection unit 11 can determine whether or not there is a change in the output value of the fuel level sensor 20 when the fuel F in the fuel tank 2 has been consumed by an amount corresponding to the threshold value. If the float 21 is stuck, the float 21 hardly moves even if the fuel F decreases and the liquid level S is displaced, and the output value does not change substantially, so the abnormality detection unit 11 detects an abnormality in the fuel level sensor 20.

[0022] As an example, the abnormality detection unit 11 calculates the difference (maximum fluctuation amount) between the maximum and minimum output values ​​within an integration period of the injection amount, and compares it with a predetermined value. If the maximum fluctuation amount is equal to or greater than the predetermined value, the abnormality detection unit 11 determines that the state of the fuel level sensor 20 is normal, and if the maximum fluctuation amount is less than the predetermined value, the abnormality detection unit 11 determines that the state of the fuel level sensor 20 is abnormal. The abnormality detection unit 11 outputs the determination result to the display 42.

[0023] If the abnormality detection unit 11 detects an abnormality in the fuel level sensor 20 based on a change in the output value when the integrated value reaches a predetermined threshold, the more fuel-efficient the vehicle 9 is, such as a hybrid vehicle, the less fuel F it consumes, so the increase in the integrated value of the injection amount is slower and a sufficient detection frequency cannot be ensured. On the other hand, if the threshold is lowered, the detection frequency increases, but the fuel level sensor 20 will be detected as abnormal even if the decrease in fuel F is small, which may result in erroneous detection of an abnormality.

[0024] Therefore, the threshold setting unit 14 sets a lower threshold for the integrated value as the absolute value of the acceleration of the vehicle 9 increases. When the absolute value of the acceleration is large, the liquid level S in the fuel tank 2 is largely displaced due to the reaction of the acceleration, so that even a low threshold is sufficient to suppress false detection and to promptly start abnormality detection.

[0025] On the other hand, when the absolute value of the acceleration is small, the displacement of the liquid level S in the fuel tank 2 due to the reaction of the acceleration is small, but because the threshold value is high, when the absolute value of the acceleration is small, more fuel F is injected and the liquid level S is sufficiently displaced. Therefore, it is possible to sufficiently suppress erroneous detection and ensure the frequency of abnormality detection of the fuel level sensor 20 even when the vehicle 9 is stopped or traveling at a constant speed.

[0026] Here, the acceleration calculation unit 13 calculates the acceleration of the vehicle 9 from the detection value of the vehicle speed sensor 41 and outputs the calculated acceleration to the threshold setting unit 14. The acceleration calculation unit 13 acquires the acceleration from the vehicle speed sensor 41, but is not limited to this, and may acquire the acceleration from an acceleration sensor instead of the vehicle speed sensor 41. Note that the threshold setting unit 14 is an example of a setting unit, and the acceleration calculation unit 13 is an example of an acquisition unit.

[0027] Since the liquid level S in the fuel tank 2 changes in response to acceleration, if the float 21 is not stuck, the output value of the fuel level sensor 20 changes in response to the change in the height position of the float 21. By setting the threshold value by the threshold value setting unit 14, the greater the acceleration, the sooner the integrated value of the injection amount reaches the threshold value, so that the abnormality detection unit 11 can quickly start the abnormality detection process of the fuel level sensor 20 when the liquid level S changes significantly, thereby increasing the detection frequency.

[0028] Furthermore, when the vehicle 9 is stopped or traveling at a constant speed, the acceleration is substantially zero, and therefore the threshold value of the integrated value becomes larger than in the above case. Therefore, the start of the abnormality detection process is delayed, but unlike the technology of the above cited document 1, the integrated value of the injection amount becomes equal to or greater than the threshold value, so that the detection frequency can be ensured.

[0029] Therefore, the ECU 1 can detect an abnormality in the fuel level sensor 20 more frequently.

[0030] Furthermore, when the integrated value becomes equal to or greater than the threshold value, the abnormality detection unit 11 instructs the injection amount calculation unit 12 to reset the integrated value, for example, to 0. The injection amount calculation unit 12 restarts the integration of the injection amount from 0 in accordance with the instruction.

[0031] The memory 15 is realized by a non-volatile memory such as a flash memory. The memory 15 stores map data 150 of the correspondence relationship between the acceleration (absolute value) and the threshold value.

[0032] The threshold value setting unit 14 accesses the memory 15, reads out the threshold value corresponding to the acceleration from the map data 150, and sets it in the abnormality detection unit 11.

[0033] (Map data) FIG. 2 is a diagram showing an example of the map data 150. In the map data 150, the larger the acceleration, the smaller the threshold value, and the smaller the acceleration, the larger the threshold value. As the acceleration approaches 0, the threshold value gradually increases so as to approach a predetermined value Mu. Also, as the acceleration increases, the threshold value gradually decreases so as to approach a predetermined value Md (<Mu). Thereby, as described above, not only is the frequency of abnormality detection of the fuel level sensor 20 ensured by an appropriate threshold value corresponding to the absolute value of the acceleration, but also the accuracy of abnormality detection is improved.

[0034] For example, in the region Xb where the acceleration is large, the threshold value is set to the lower predetermined value Md. At this time, when comparing the displacement of the liquid level S in the fuel tank 2 with the region Xa where the acceleration is small, although the displacement of the liquid level S due to the injection of the fuel F is small, the displacement of the liquid level S due to the acceleration is large.

[0035] On the other hand, in the region Xa where the acceleration is small, the threshold value is set to the higher predetermined value Mu. At this time, when comparing the displacement of the liquid level S in the fuel tank 2 with the region Xb where the acceleration is large, although the displacement of the liquid level S due to the acceleration is small, the displacement of the liquid level S due to the injection of the fuel F is large. Therefore, it is possible to detect the abnormal state of the fuel level sensor 20 with high accuracy.

[0036] The relationship between the absolute value of acceleration and the threshold value is not limited as long as the threshold value when the absolute value of acceleration is large is smaller than the threshold value when the absolute value of acceleration is small. Furthermore, the threshold value is not limited to the map data 150, and may be calculated, for example, from a predetermined calculation formula.

[0037] (Example of detecting an abnormality in a fuel level sensor) 3 is a time chart showing an example of abnormality detection of the fuel level sensor 20. FIG. 3 shows the vehicle speed (m / s) and acceleration (m / s) versus time (ms). 2 ) (depicted as large, medium, and small), the integrated value of the injection amount (ml), the output value (V) of the fuel level sensor 20 ("sensor output value"), and changes in the state of the fuel level sensor 20 ("sensor state") are shown. Note that the period between times 0 and T5 is the integration period of the injection amount.

[0038] The acceleration is obtained as the amount of change in vehicle speed over time, for example, but may also be obtained directly from an acceleration sensor, etc. During the period from time 0 to T5, the acceleration is smallest at times 0 to T1 and T4 to T5, and is largest at times T2 to T3. Also, the acceleration is in the intermediate range between the maximum and minimum at times T1 to T2 and T3 to T4.

[0039] The threshold values ​​THa-THe for detecting an abnormality in the fuel level sensor 20 are calculated from the map data 150 according to the acceleration. As described above, the threshold values ​​THa-THe are lower as the acceleration increases and higher as the acceleration decreases. Therefore, the threshold value THa is the lowest at times T2-T3, and the threshold values ​​THd, THe are the highest at times 0-T1 and T4-T5. Moreover, the threshold values ​​THb, THc at times T1-T2 and T3-T4 are in the intermediate range between the maximum and minimum values.

[0040] In this example, the integrated value of the injection amount increases at a constant rate of increase, but is not limited to this, and the rate of increase may vary depending on the time. The integrated value of the injection amount returns to 0 each time it reaches the thresholds THa to THe. Note that the thresholds THa to THe may be calculated based on the average value of acceleration during the period until the integrated value of the injection amount reaches the thresholds THa to THe, that is, within each integration interval.

[0041] The sensor output value decreases as the integrated value of the injection amount increases. Also, the greater the acceleration, the greater the change in the height position of the float 21 due to the displacement of the liquid level S, and therefore the greater the change in the sensor output value. If the float 21 is not stuck, the sensor output value changes, and therefore the fuel level sensor 20 is determined to be in a normal state. On the other hand, if the float 21 is stuck, the sensor output value does not substantially change, and therefore the fuel level sensor 20 is determined to be in an abnormal state.

[0042] In this example, the sensor output value changes from time 0 to T3, so the sensor state is determined to be normal. On the other hand, the sensor output value does not change from time T3 to T5, so the sensor state is determined to be abnormal. Note that the timing for executing the abnormality detection process for determining the sensor state is immediately after the times T1 to T5 when the integrated value of the injection amount reaches the threshold values ​​THa to THe.

[0043] In this way, the greater the acceleration, the lower the threshold values ​​THa-THe, and the sooner the integrated value of the injection amount reaches the threshold values ​​THa-THe. Therefore, the abnormality detection unit 11 can quickly start the abnormality detection process of the fuel level sensor 20 to increase the detection frequency. Also, when the vehicle 9 is stopped or traveling at a constant speed, the acceleration is substantially zero, so the threshold values ​​THa-THe of the integrated value become high and the start of the abnormality detection process becomes slower, but the integrated value becomes equal to or greater than the threshold values ​​THa-THe, so the detection frequency can be ensured.

[0044] Therefore, the ECU 1 can detect an abnormality in the fuel level sensor 20 more frequently.

[0045] (Fuel level sensor abnormality detection process) 4 is a flowchart showing an example of a process for detecting an abnormality in the fuel level sensor 20. This process is executed, for example, periodically.

[0046] First, the acceleration calculation unit 13 calculates the acceleration from the vehicle speed detected by the vehicle speed sensor 41 (step St1). Next, the threshold setting unit 14 sets a threshold based on the acceleration and the map data 150 (step St2). Next, the injection amount calculation unit 12 integrates the injection amount of the fuel F (step St3). Note that the processes of steps St2 and St3 may be performed simultaneously in parallel.

[0047] Next, the abnormality detection unit 11 compares the integrated value with a threshold value to determine whether or not the abnormality detection process is possible (step St4). If the integrated value is less than the threshold value (No in step St4), it is determined that the liquid level S has not displaced sufficiently and the abnormality detection process cannot be performed, and each process from step St1 onwards is executed again. This causes the integration of the injection amount and the setting of the threshold value to be repeated.

[0048] Furthermore, if the integrated value is equal to or greater than the threshold value (Yes in step St4), the abnormality detection unit 11 instructs the injection amount calculation unit 12 to reset the integrated value to 0 (step St5). This enables the injection amount calculation unit 12 to integrate the injection amount from the beginning. When the integrated value reaches the threshold value, the abnormality detection unit 11 determines that the liquid level S has displaced sufficiently to enable the execution of the abnormality detection process, and executes the following process.

[0049] Next, the abnormality detection unit 11 calculates the maximum fluctuation amount of the output value of the fuel level sensor 20 within the integration period of the injection amount (step St6). For example, the abnormality detection unit 11 stores the output value in the memory 15, and calculates the difference between the maximum value and the minimum value of the output value within the period from 0 to the threshold value as the maximum fluctuation amount.

[0050] Next, the abnormality detection unit 11 compares the maximum fluctuation amount with a predetermined value (step St7) to determine the state of the fuel level sensor 20. If the maximum fluctuation amount is equal to or greater than the predetermined value (Yes in step St7), the abnormality detection unit 11 determines that the height position of the float 21 is changing along with the displacement of the liquid level S of the fuel F in the fuel tank 2, and determines that the fuel level sensor 20 is in a normal state (step St8).

[0051] Furthermore, if the maximum fluctuation amount is less than the predetermined value (No in step St7), the abnormality detection unit 11 determines that the height position of the float 21 has not changed regardless of the displacement of the liquid level S of the fuel F in the fuel tank 2, and determines that the fuel level sensor 20 is in an abnormal state due to the sticking of the float 21 (step St9). Note that the predetermined value is preset to a sufficiently high accuracy value taking into consideration the rattling of the float 21 and the like so as to prevent erroneous detection.

[0052] Next, the abnormality detection unit 11 displays the result of the determination of the state of the fuel level sensor 20 on the display 42 (step St10). This allows the driver of the vehicle 9 to check the state of the fuel level sensor 20. In this manner, the abnormality detection process for the fuel level sensor 20 is performed.

[0053] The above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this embodiment and can be modified in various ways without departing from the scope of the present invention. [Explanation of symbols]

[0054] 1 ECU (abnormality detection device) 3 Engine 10 Level detection section 11 Anomaly detection unit (detection unit) 12 Injection amount calculation section (calculation section) 13 Acceleration calculation unit (acquisition unit) 14 Threshold setting unit (setting unit) 20 Fuel level sensor (sensor)

Claims

[Claim 1] 1. An abnormality detection device for a sensor that detects a remaining amount of fuel based on the position of a float that floats on a fuel surface in a fuel tank of a vehicle, comprising: a calculation unit that calculates an integrated value of the fuel injection amount; An acquisition unit that acquires an acceleration of the vehicle; a detection unit that detects an abnormality of the sensor based on a change in an output value of the sensor when the integrated value reaches a threshold value; A setting unit that sets the threshold value lower as the absolute value of the acceleration increases. Sensor abnormality detection device.

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